台灣北部地區地形多山，易對雷達電磁波產生遮蔽的效應，尤其是雪山西麓一帶，常有雷達回波低估的現象。中央大學大氣系都卜勒氣象雷達位於雪山山脈西側，可以大幅改善五分山雷達站觀測回波低估的問題。此雷達觀測範圍可涵蓋桃竹苗及大台北地區，與氣象局之間的數據線路連結亦已完成，配合雨滴譜儀的校驗，透過氣象局QPESUMS系統與五份山雷達資料互補，可產生北部地區高解析度最佳的降水估計。中央大學大氣系透過氣象局及水利署合作，將目前雷達之都卜勒功能，進一步提升至偏極化功能，成為北部地區第一部偏級化/都卜勒雷達。並且將此研究用雷達觀測效能提升，並提高作業效率，以保持長時間的觀測，即時提供雷達觀測資料至氣象局雷達網連資料系統，以改善北部地區降雨估計。故本委辦計畫之目的，是要維護中央大學偏極化/都卜勒氣象雷達，並提供綜合北部雷達站及雨量計雨滴譜儀降水估計流程、數值程式和即時降雨率分布產品，以提供上游正確降雨資料輸入「水文水資源資料管理供應系統」。此外，台電公司電力綜合研究所建立之閃電資料，可用以協助區分降雨類別、判別對流雲之生命週期，因此今年將取得台電閃電樣本資料，研發並分析資料特性及資料流程可行性。預期加入閃電資料後應可助於降雨預報之準確度。 The rainfall estimate products from the Central Weather Bureau radar observation have been provided to forecast center of Bureau and other agencies such as the Water Resources Agency and Disaster Mitigation Center. However, because of the different rain drop distribution characteristics of each rainfall event, such as heavy rain during Typhoon Mei-Yu and severe thunderstorms, etc., the variation of the relations between radar reflectivity and the rainfall rate estimation (Z-R relation) is quite large. So the single formula for the Z-R relation often underestimates the rainfall during heavy rain. The complex terrain also cause ground clutter and the blocking of radar beam energy, these factors also induce rainfall estimate errors. In the first year of this project, our work will be focused on the Polarization upgrade of the NCU Doppler radar and the application of disdrometer observation. The polarimetric variables observed by this new kind radar can provide drop size distribution, drop oblateness, and hydrometer types in a precipitation system. The real time drop size distribution can be used to calibrate the conventional weather radar at Wufansen. Because of the importance of polarimetric radar to the severe weather forecasting, this project will also be the risk reduction project for the future possible precipitation radar development of Water Resources Agency and Central Weather Bureau radar application. 研究期間：9304 ~ 9312
